1. Field of the Invention
This invention relates to an information signal processing method and apparatus, and more particularly, to an information signal processing method and apparatus which detects an error in an information signal.
2. Description of the Prior Art
An error detection method using CRCC (cyclic redundancy check code) has been known as a method to detect an error in information data which is generated on a transmission channel in transmission or recording/reproduction of an information signal, particularly digital information data.
The principle of the error detection for information data using the CRCC comprises dividing the information data by a predetermined formula to generate a polynominal and using the remainder of the division as check data.
That is, when the transmitted information data to which the CRCC has been added are divided at the reception side, the data are divisible with a remainder "0" if no error is generated in the information data on the transmission channel, and the data are not divisible with a remainder of "0" if an error is generated in the information data on the transmission channel. Hence, by using the remainder, it is possible to detect an error in the information data which has been generated on the transmission channel.
As for the data error detection capability of the CRCC, when check data of m (m is a positive integer) bits have been added, the generation of a burst error of m bits or less can be detected with a probability of 100%, and the generation of a burst error of (m+1) bits or more cannot be detected with a probability of about 1/2.times.m.
That is, if it is assumed that a data error of any pattern is generated with the same probability, the probability that the detection of a data error becomes impossible can be considered to be about 1/2.times.m in total.
As described above, in data error detection using only the CRCC, the detection of a data error is not always possible with a predetermined probability.
Particularly, when check data comprise m bits as described above, it is impossible to detect whether or not an error is generated in data for about 1/2.times.m of the data if a burst error having a bit length longer than m bits has been generated, causing a misoperation in an apparatus at the reception side when the information data are identification information (ID) data or the like.